A congenital dilated imperforate submandibular duct is a rare condition that presents early in neonates. Treatment can vary considerably from other lesions more commonly found in the floor of the mouth. Here we describe the case of a 1-week-old neonate with a fluctuant lesion in the
floor of the mouth, ultimately diagnosed as a congenital dilated imperforate submandibular duct. We then discuss the imaging characteristics, differential diagnosis, and treatment of the condition.

Neurographics is the peer-reviewed, bimonthly educational journal of the American Society of Neuroradiology. The journal comprises articles selected from material presented at the ASNR Annual Meeting. Neurographics also publishes other high-quality submissions that are primarily educational and have a high emphasis on a pictorial approach. Neurographics offers CME credit for reading review articles and completing quiz-based self-assessment activities.